1. Technical Field
The present disclosure relates to a touch sensing apparatus, and more particularly, to a touch sensing apparatus capable of improving the efficiency of a process of determining a touch sensing signal of a touch screen panel.
2. Related Art
A touch screen panel may be configured to sense a touch in a capacitive manner.
The capacitive touch screen panel includes driving electrodes for receiving a driving signal and sensing electrodes for outputting a touch sensing signal, and senses a touch using coupling capacitors formed between the respective driving electrodes and the sensing electrodes.
For example, when the driving electrodes and the sensing electrodes of the touch screen panel are configured to cross each other, the coupling capacitors are formed at the respective nodes where the driving electrodes and the sensing electrodes cross each other. The capacitance of the coupling capacitor is changed when the corresponding node of the touch screen panel is touched.
The driving electrodes receive driving signals with the same magnitude and frequency. When there is no touch on the nodes at which the coupling capacitors are formed, the same touch sensing signals are outputted from the sensing electrodes. When there is a touch on a specific node, the capacitance of the coupling capacitor of the corresponding node is changed, and a touch sensing signal outputted from the sensing electrode of the corresponding node is changed according to the change of the capacitance. A touch sensing apparatus senses the touch of the corresponding node by determining the change of the touch sensing signal.
The touch sensing signal may contain various frequencies of noise while being influenced by noise caused by a parasitic capacitor and parasitic resistor of the touch screen panel. Thus, the touch sensing apparatus must be able to accurately determine the touch sensing signal while distinguishing between the touch sensing signal and noise.
The touch sensing signal is also influenced by a load of the touch screen panel. Although touch sensing signals are generated from the same sensing electrode, the touch sensing signals may have a difference therebetween depending on the touch positions. That is, a touch sensing signal generated through a touch on a node close to an output terminal of a sensing line is different from a touch sensing signal generated through a touch on a node away from the output terminal of the sensing line. Therefore, in order for the touch sensing apparatus to accurately determine a touch sensing signal, the influence of the load on the touch sensing signal must be reduced.